(1) Field of the Invention
The present invention relates to the microbiological industry, more particularly to methods of preparing aminoacids and, more specifically, to a fermentation method for preparing L-alanine
(2) Background of the Related Art
Known in the art are methods for preparing L-alanine by way of transformation from aspartic acid using immobilized cells of microorganisms possessing a .beta.-decarboxylase activity (U.S. Pat. No. 3,898,128).
Such known methods are multi-stage ones which is associated with the necessity of producing, for example, in the first stage of the process, L-aspartic acid from ammonium fumarate by transformation with the use of aspartase and, in the second stage of the process - transformation of the resulting L-aspartic acid into L-alanine by means of L-aspartate-.beta.-decarboxylase (Progress in Industrial Microbiology, v. 24, 1986, Tokyo, J. Chibata, T.Tosa, T. Kakimoto "Alanine", p. 224-232).
Known in the art is a method for recovering L-alanine for a racemic mixture, wherein D,L-alanine is subjected to acetylation and then, by means of an enzyme - aminoacylase, acetyl-L-alanine is selectively hydrolyzed to give L-alanine. Afterwards, L-alanine is separated from acetyl-D-alanine (U.S. Pat. No. 3,386,888).
This is a multi-stage process necessitating preparation of intermediate D,L-alanine, acetyl-D,L-alanine, aminoacylase enzyme, thus making the process more complicated and expensive.